Process for cracking petroleum oil



Nov. l1, 1930.' R. T. PoLLocK l Y 1,781,128

PROCESS FOR CRACKING PETRGLEUM OIL Filed March 9, 1927 ATTORNEY.

Patented Nov. 11,- 1930 PATENT OFFICE ROBERT T. POLLOCK, OF N'EW YORK, N. Y.,

ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPAN Y, 0F CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA 4PROCESSFOR CRACKING PETROLEUM OIL Application filed March 9, 1927. Serial No. 173,921.

This invention relates to improvements in process for cracking petroleum oil and refers more particularly to that type of process in which the generated `vapors are subjected to reflux condensing action and the reiux condensate, that is to say the incompletely converted oil constituents subjected to fur- -ther cracking reaction.

This application isa continuation in part of my earlier application Serial Number 431,838, filed December 20, 1920.

With certain types of petroleum oil. the reflux condensate produced in the cracking operation is more desirably subjected to fur` ther cracking reaction under different temperatures and pressures than is the original oil. By means of the present process, this reiux condensate can be separately cracked as part of a continuous process and under different conditions of temperature and pressure than the raw oil. As a further feature of the invention, the generated vapors .are subjected to a double reflux condensing action in which the heaviest 'portions of the vapors are condensed and separately cracked while the intermediate portion of the vapors, i. e., those lighter than the heaviest but not yet suficiently cracked and therefore heavier than the lightest, are separately condensed. subjected to further cracking under still different conditions of temperature and pressure.

In the drawing, the single figure shows a somewhat diagrammatic view partly in side elevation and partly in vertical section of my improved apparatus.

Referring in detail to the drawing, A, B and C designate three separate furnaces. In

the furnace A is mounted aheating coil 1, as

for example, a continuouscoil of 2"` to 6" pipe. This coil is fed from the charging pump 2, connected to the raw oil supply by inlet line 3 and delivering the raw oil to the heating element through the feed line 4 having throttle valve 5. The discharge side of the coil is connected by transfer line 6 having throttle valve 7 to vapor chamber 8. This vapor chamber 8 is provided with liquid residue drawofl` pipe 9 controlled by throttle valve 10. It also has vapor outlet pipe 11 and downwardly inclined extension pipe 11 having throttle valve 12 and connected to the lower'side of the dephlegmator 13. The upper end of the dephlegmator 13 is connected by vapor pipe 14 having throttle valve 15 to a partial condenser or refiux condenser 16. The vapor space of this condenser is connected by pipe 17 to throttle valve 18, final condenser coil 19 seated in Water condenser 2.0. The lower end of the coil 19 is connected to the upper part of receiver 21. This receiver 21 has liquid level gauge 22, liquid drawoii' pipe 23, having throttle valve 24 and gas outlet pipe 25, having throttle valveV 26.

Referring back to the dephlegmator 13, to its lower end is connected a reflux condensate pipe 27, which leads to the inlet side of the heating coil 28 mounted in the furnace C. A throttle valve 29 is interposed in the line 27. There is likewise interposed in this line a pump 30 provided at either side with valves 31 and 32, whereby the reflux condensate may be pumped under increased pressure, if desired. A by-passline 33 having throttle valve 34 is provided for by passing the pump, if desired. The discharge side of the coil 28 is connected by transfer line 35 having throttle valve 36 to vapor chamber 37. This vapor chamber 37 is provided with liquid drawo pipe 38 controlled by throttle valve 39. The upper end of the vapor chamber is connected by vapor pipe 40 and downwardly inclined pipe 41 having throttle valve 42, to the lower side of a dephlegmator 43. This dephlegmator 43 is provided with vapor outlet pipe 44 having throttle valve 45, which pipe 44 is connected to final condenser coil 46 seated in condenser box 47. The lower end of the coil is connected by pipe 48 having throttle valve 49 to the upper part of receiver 50. This receiver 50 has liquid drawoif pipe 51 controlled by throttle valve 52 and gas outlet pipe 53 controlled by throttle valve 54.

Referring back to the dephlegmator 13, I have heretofore stated that the reflux condensate from said dephlegmator can` be delivered through pipe 27 and pump 31 or line 33 to the inlet side of the heating coil 28. It also may be delivered elsewhere, to wit. to

a suitable receptacle (not shown) by means of branch 106 having throttle valve 107. In this case the valve 29 interposed in the end of pipe 27 will be closed. 1

Referring back to the dephlegmator 43, to its lower end is connected reiux return ipe 55 in which is interposed a pump 56 have ing at either side valves.57 and 58. The pump may be by-passed by pipe 59 having valve 60. This line 55 connects to extension 55) leading to the heating coil 61 seated in furnace B. This coil may be of the same construction as the other two. The discharge side of this coil is connected by transfer line 63 having throttle valve 64 to an expansion or vapor chamber 65. This expansion chamber 65 has `a liquid drawoifpipe 66 controlled .by throttle valve 67. It is also provided with the vapor outlet pipe 68 and connecting downwardly inclined pipe 69 furnished with throttle valve 70 and leading to the lower sideof a dephlegmator 71. f The upper end of the dephlegmator is connected by vapor pipe 72 having coil 74 seated in condenser box 75. The lower end of the coil is connected by pipe 76 having throttle valve 77 to the top of receiver 78. This receiver 78 has liquid draw-off pipe 79 controlled by throttle valve 80 and gas outlet pipe 81 controlled by throttle valve 82.

The lower end of the dephlegmator 71 is connected by reflux condensate pipe 83 having throttle `valve 84 to a second return pipe 85 leading back to the pipe 55', whereby it may be returned to the heating coil 61. The line 83 is also provided with the branch pipe 86 having throttle valve 87 connected to any suitable receptacle (not shown), whereby the reflux condensate may be led elsewhere than delivered to the coil 61. In this case a valve 88 in the line 85 can be closed and valves 84 and 87 regulated. In the pipe 85 is interposed a pump 89 having at either side, valves 90 and 91, whereby the reux condensate may be returned .to the pipe 55 under pressure. This pump xmay be by-passed by means of the pipe 92 having throttle valve 93. A throttle valve 94 is interposed in the pipe 55. I have heretofore stated that the reiux condensate from the pipe 55 may be delivered tothe pipe 55. It also may be delivered elsewhere, to-wit z--to a suitable receptacle, (not ,show-n), by means of branch 95 having throttle valve 96. In this case the valve 97 interposed in the end ofthe pipe55 will be closed.

Referring back toV the partial condenser 16, to its lower side is connected condensate return pipe 98. In this pipe line 98 is interposed a pump 99 having lsuitable valves at either side thereof and also provided with the by-pass lin'e 100 having valve 101. The lower end of the pipe 98 is connected as shown at 102 to the line 55', provided with control valve 103. The reflux condensate instead of being returned tothe pipe 55 may throttle valve 73 to condenser the heating tubes,

1 the hot oil is passed to the vapor chamber 8 where the vaporsseparate. The vapors pass thence to the irst dephlegmator 13 where they can be subjected to fractionation. This fractionation may be helped by the introduction of a cooling medium in the dephlegmator in a well-known manner. The uncondensed portions are passed to the partial A condenser 16 and the still uncondensed portions are passed to the condenser 19 "and thence to the receiver 21. All of the elements so far referred to may be maintained under the same pressure or, if desired, dierential pressures may be maintained on said elements. The relux condensate from the dephlegmator 13 may be passed to the heating coil 28 by means of the pump 30, or of the by-pass line 33, according to the relative pressures maintained on the dephlegmator 13 and the second heating coil 28. In the second heating coil 28 the reflux condensate from dephlegmator 13 is subjected to further conditions of conversion passing thence to the vapor. chamber 37 and to the dephlegmator 43. The uncondensed portions from dephlegmator43 will pass into the condensing coil 46 and thence to the receiver 50. This part ofthe system from the coil 28 to receiver 50 may be maintained under the same pressure or each step of this part of the system can be maintained under differential pressure. The pressure in this part of the system may be higher or lower than that maintained in the part of the system from heating coil 1 to receiver 21, and, if the differential pressures are maintained on these two parts of the system, the pressure on a step of the part of the skystem from coil 28 to receiver 50 can be hig er or lower than the pressure on the corresponding step of the part of the system from coil 1 to receiver 21. On the other hand, and according to the material treated in coil 1, and also to the characteristics of the reflux condensate passed from dephlegmator. 13 throughline 27 into the lsecond heating coil 28, and also according to the characteristics of the product which it is desired to produce in the second part of the system from heating coil 28 to receiver 50, the temperature to which the refiux condensate from dephlegmator 13 is subjected in the second heating coil 28 may be higher or lower, or the same as that to which the oil was subjected in heating coil 1.

The reiiux condensate formed in the dephlegmator 43 of the second part of the system may be passed to the heating coil 61 by means of pump 56 or by-pass 59 according to the relative pressures maintained on dephlegmator 43 and heating coil 61. Here the reflux condensate will be heated to such temperature as will cause further conversion thereof, and it will thence pass into chamber 65 and the vapors into dephlegmator 71. The uncondensed portions will pass out of the dephlegmator 71 into the condenser 74, and Athence into the receiver 78. The partof the system Ffrom heating tubes 61 to receiver 78 can be maintained under an equalized pressure or the various steps of this part of the system can be maintained under differential pressures. In the same manner as has been heretofore described in relation with the first and second parts of the system, the third part of the system from heating coil 61 to receiver 78 can be maintained under the same pressure as either one of the first or second parts of the system. In other words, the part of the system from heating coil 61 to receiver 78 can be maintained unfder the same pressure as part of the system from coil 1 to receiver 21 and, if in the same operation, the second lpart of the system from .heating coil 28 to receiver 50 is main- -tained 'at a higher or lower pressure than the first part of the system from heating coil 1 to receiver 21, it will also be respectively at a higher or lower pressure than the third part of the system from heating coil 61 to receiver 78. In another method of operation, the third part of the system, from heating coil 61 to receiver 78, can be maintained under a pressure lowerv or higher than the pressure maintained on both the rst part of the system from heating coil 1 to receiver 21, and the second part of the system from heating coil 28 to receiver 50.

Again, in another method of operation, thepressure maintained on the three parts of the system can be, for instance, progressively increasing or decreasing from the first part of the system, from heating coil 1 to receiver 21, up tothe second part ofthe system, from heating coil 28 to receiver 50, the third part of the system from heating coil 61 vto receiver 78 being then at a pressure intermediate those maintained on the two other parts of the system.

The temperature at which the various cuts of condensates are heated respectively in heating coils 28 and 61 are regulated according to the characteristics of the material treated, and of the products desired. For instance, the temperature at which the oil is converted in the various heating coils can be progressively increasin the heating coil 28 being maintained at aigher temperature than the heating cpil 1, and the oil passed through heatingcoil 61 being subjected to a higher temperature than that passed through coil 28'.

As another method of operation, the reliux condensate subjected to treatment in heating Asubjected in heating coil 28, but, at the same time, lower than that at which the oil is subjected in heating coil 1. In a-further method of operation, the reflux condensate from dephle'gmators 16, 43, and 71 may be subjected in heating coil 61 to a temperature lower than that at which the reflux condensate from dephlegmator 13 is subjected in heating coil 28, and, at the same time, higher than that at which the oil is subjected in heating coil 1.

In the methods of operation heretofore referred to, and which are in no way limiting the scope of the invention on account of the wide variations which can be brought to the method of operation adopted to carry out the process, I have preferably subjected to further treatment under independent conditions of temperature and pressure, all the various cuts of reflux condensate formed in the operation of the process.

However, in one of the preferred methods forcarryingout the process it may be desirable to subject to further-treatment only selected fractions of the reflux condensate formed in the process while the other fractions are withdrawn from the apparatus and 'discharged to storage. To this effect I have heretofore referred to valve-controlled draw-oft' lines 106, 104, 95, and 86 connected respectively to 'the reflux draw-olf lines from dephlegmators 13, 16, 43, and 71. By the proper manipulation of the valves shown on these branch lines, the reflux'from each of the aforementioned dephlegmators can be withdrawn from the process and evacuated to `storage tanks (not shown).

For instance, in one method of operation, b opening valves 107 on branch line 106 and c osing valve 29 on line 27, the reflux from dephlegmator 13 can be withdrawn to storage, and in this case the second part of the system from heating coil 28 to receiver 50 will be cut oil' from the operation. Valve 97 online 55 will also be closed. At the same time, the reflux condensate from partial condenser 16 will be directed to heating coil 61 for further treatment as above described, valve 105 on branch line 107 being closed.

On the other hand, it isr possible `tosubject the reflux condensate from dephlegmator 13 to further treatment in the second part of the system from heating coil 28 to receiver 50 `and again subjectthe reflux condensate from the dephlegmator 43 of said second part of the system to further treatment in heating coil 61, while the reiiux condensate from the partial condenser 16 will vbe withdrawn from the process by opening valve 105 on branch line 104 and closing valve 103 on line 55.

' In another method of operation, the reiux condensates from dephlegmators 13 and 16 can be respectively treated in heating coils 28 and 61while the reflux condensates from dephlegmato-rs 43 and 71 are withdrawn from the process through lines 95 and 86 respectively.

It is not deemed necessary to describe herein all the various methods of operation which can be utilized to carry out the process as regards the treatment of reflux condensate from the various dephlegmators of the process under further conditions of conversion. It is believed Athat the above description Y of the process, together-with the drawing, will enable any one skilled in the art to adopt the method of operation best suited to the result desired.

No specific illustration of the pressures and temperatures of the `various parts of the system have been heretofore given since they may be varied widely from one operation to another. The various fractions of oil can be subjected in the various portions ofthe system to pressures from 100 to 1000 pounds, and in various heating coils temperatures of from 600 toy 10000 F. may be used. Furthermore,

` while the heating coil and the vapor chamber of each part of the system may be maintained under superatmospheric pressure, the dephlegmators, condensers, 'and receivers of each part of the system may be maintained under atmosphericl or subatmospheric pressure. l

'I claim as my invention 1. A process for cracking high boiling point hydrocarbon oils to produce substantial yield of low boiling point oils having the characteristics of gasoline, comprising continuously lsupplying the high boiling point oil 'ecting the same to a primary cracking treatment; separating the products of said primary cracking treatment into at least three components, that is constituents having the characteristics of gasoline, intermediate constitutents heavier than gasoline and residuum, removing the gasoline-like constituents and the residuum products from the zone of cracking, continuing the cracking of the intermediate constituents heavier than gasoline in successive stages, 'removing from each stage the gasoline-like constituents and the residual products heavier than said intermediate products whereby each succeeding stage receives for cracking only intermediate products heavier than gasoline of the previous cracking, and controlling the cracking conditions maintained on the oil during said primary cracking treatment and on the intermediate constituents undergoing treatment in said succeeding stages so as to cracking reaction are obtain a substantial yield of low boiling point distillate.

2. A process for cracking heavy oil to pro-I ing stage of onlyT the intermediate products of the preceding stage, whereby the desirable products and the'undesirable products of the removed from the zone of cracking as formed and only intermediate v products of cracking subjected to prolonged cracking treatment.

ROBERT T. POLLOCK.

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